Path: utzoo!attcan!uunet!smsdpg!seg
From: seg@smsdpg.uu.net (Scott Garfinkle)
Newsgroups: comp.protocols.nfs
Subject: PC-NFS Locking Problem
Message-ID: <183@smsdpg.uu.net>
Date: 18 Jan 89 17:50:00 GMT
Organization: SMS Data Products Group, Reston VA
Lines: 52

Has anybody done anything with sharing/locking under DOS 3.x and PC-NGS?
The manual specifically states that advisory locking is supported via the
standard DOS function calls.  However, I wrote the following simple program
to test this stuff and found that my requests for locks are completely
ignored -- this program, run from two different PC nodes at the same time,
returns successfully from acquiring a lock on the same file on out server!
Am I missing something?  Setup: AT clone and PC clone, both running PC-DOS
3.3 with SHARE installed and PC-NFS v3.0; Server==Sun 3/180 running SunOS 4.0.
(PCs are using the WD8003 ethernet cards.)  Code for test follows (for MSC5.1)
		Scott E. Garfinkle
		SMS Data Products Group, Inc.
		uunet!smsdpg!seg (smsdpg!seg@uunet.uu.net)(
-----------
#include <stdio.h>
#include <sys\locking.h>
#include <fcntl.h>
#include <io.h>
#include <share.h>
#include <sys\types.h>
#include <sys\stat.h>

char *cmdname;

main(int argc, char **argv)
{
	int fd;
	long flen;
	extern int errno;

	cmdname = *argv;
	if(argc != 2) {
		fprintf(stderr,"Usage: %s <file-to-lock>\n",cmdname);
		exit(1);
	}
	if((fd = sopen(argv[1],O_RDWR,SH_DENYWR)) == -1) {
		fprintf(stderr,"%s: Couldn't open %s for read/write, errno=%d.\n",
			cmdname,argv[1],errno);
		exit(2);
	}
	printf("Opened %s for read/write in Deny Write mode.\nHit any key to continue.", argv[1]);
	fflush(stdout);
	(void) getch();
	putch('\n');
	putch('\r');
	flen = filelength(fd);
	if(locking(fd,LK_LOCK,flen)) {
		fprintf(stderr,"%s: Failed to lock %ld bytes, errno=%d.\n",
			cmdname,flen,errno);
		exit(3);
	}
	printf("Locked %ld bytes.  Hit any key to continue.", flen);
	fflush(stdout);
	(void) getch();
	exit(locking(fd,LK_UNLCK,flen));
}